LT1083/84/85 Fixed
3A, 5A, 7.5A Low Dropout
Positive Fixed Regulators
FEATURES
s
s
s
s
s
s
s
s
DESCRIPTION
The LT1083 series of positive adjustable regulators are
designed to provide 3A, 5A and 7.5A with higher efficiency
than currently available devices. All internal circuitry is
designed to operate down to 1V input to output differential
and the dropout voltage is fully specified as a function of
load current. Dropout is guaranteed at a maximum of 1.5V
at maximum output current, decreasing at lower load
currents. On-chip trimming adjusts the output voltage to
1%. Current limit is also trimmed, minimizing the stress
on both the regulator and power source circuitry under
overload conditions.
The 1083 series devices are pin compatible with older
three-terminal regulators. A 10µF output capacitor is
required on these new devices; however, this is usually
included in most regulator designs.
Unlike PNP regulators, where up to 10% of the output
current is wasted as quiescent current, the LT1083 quies-
cent current flows into the load, increasing efficiency.
Three-Terminal 3.3V, 3.6V, 5V and 12V
Output Current of 3A, 5A or 7.5A
Operates Down to 1V Dropout
Guaranteed Dropout Voltage at Multiple Current Levels
Line Regulation: 0.015%
Load Regulation: 0.1%
100% Thermal Limit Functional Test
Adjustable Versions Available
APPLICATIONS
s
s
s
s
High Efficiency Linear Regulators
Post Regulators for Switching Supplies
Constant Current Regulators
Battery Chargers
DEVICE
LT1083
LT1084
LT1085
OUTPUT CURRENT*
7.5 Amps
5.0 Amps
3.0 Amps
*For a 1.5A low dropout regulator see the LT1086 data sheet.
TYPICAL APPLICATION
5V, 7.5A Regulator
INPUT/OUTPUT VOLTAGE DIFFERENTIAL (V)
Dropout Voltage vs Output Current
2
V
IN
≥
6.5V
LT1083-5
5V AT 7.5A
+
10µF
+
22µF*
TANTALUM
*REQUIRED FOR STABILITY
1
LT1083/4/5 TA01
0
0
U
U
U
I
FULL LOAD
/2
OUTPUT CURRENT (A)
I
FULL LOAD
1083/4/5 TA02
1
LT1083/84/85 Fixed
ABSOLUTE
MAXIMUM
RATINGS
Power Dissipation............................... Internally Limited
Input Voltage (Note 1) ............................................. 30V
Operating Input Voltage
3.3V, 3.6V Devices ............................................ 20V
5V Devices ........................................................ 20V
12V Devices ...................................................... 25V
Operating Junction Temperature Range
“C” Grades
Control Section ............................... 0°C to 125°C
Power Transistor ............................. 0°C to 150°C
“M” Grades
Control Section ........................... –55°C to 150°C
Power Transistor ......................... –55°C to 200°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Note 1:
Although the devices maximum operating voltage is limited, (20V
for a 3V, 5V device, and 25V for a 12V device) the devices are guaranteed
to withstand transient input voltages up to 30V. For input voltages greater
than the maximum operating input voltage some degradation of
specifications will occur. For input/output voltage differentials greater than
15V, a minimum external load of 5mA is required to maintain regulation.
PRECONDITIONING
100% Thermal Limit Functional Test.
PACKAGE/ORDER INFORMATION
V
IN
2
CASE IS
OUTPUT
ORDER PART NUMBER
LT1083CK-5
LT1083CK-12
LT1083MK-5
LT1083MK-12
LT1084CK-5
LT1084CK-12
LT1084MK-5
LT1084MK-12
LT1085CK-5
LT1085CK-12
LT1085MK-5
LT1085MK-12
TAB IS
OUTPUT
FRONT VIEW
3
2
1
P PACKAGE
3-LEAD TO-3P PLASTIC
1
GND
K PACKAGE
2-LEAD TO-3 METAL CAN
θ
JA
= 35°C/W
FRONT VIEW
θ
JA
= 45°C/W
FRONT VIEW
3
TAB IS
OUTPUT
2
1
M PACKAGE
3-LEAD PLASTIC DD
V
IN
V
OUT
GND
TAB IS
OUTPUT
3
2
1
T PACKAGE
3-LEAD PLASTIC TO-220
V
IN
V
OUT
GND
θ
JA
= 50°C/W
LT1084CT-3.3
LT1084CT-5
LT1084CT-12
LT1085CT-3.3
LT1085CT-3.6
LT1085CT-5
LT1085CT-12
θ
JA
= 30°C/W*
* WITH PACKAGE SOLDERED TO 0.52IN
2
COPPER AREA OVER BACKSIDE GROUND
PLANE OR INTERNAL POWER PLANE.
θ
JA
CAN
VARY FROM 20°C/W TO > 40°C/W DEPENDING
ON MOUNTING TECHNIQUE.
Consult factory for Industrial grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER
Output Voltage
CONDITIONS
LT1084-3.3
LT1085-3.3
LT1085-3.6
I
OUT
= 0mA, T
J
= 25°C, V
IN
= 8V (K Package Only)
0
≤
I
OUT
≤
5A, 4.8V
≤
V
IN
≤
15V (Note 8)
V
IN
= 5V, I
OUT
= 0mA, T
J
= 25°C (K Package Only)
4.8V
≤
V
IN
≤
15V, 0
≤
I
OUT
≤
3A (Note 8)
V
IN
= 5V, I
OUT
= 0mA, T
J
= 25°C (K Package Only)
5V
≤
V
IN
≤
15V, 0
≤
I
OUT
≤
3A (Note 8)
5V
≤
V
IN
≤
15V, 0
≤
I
OUT
≤
3A, TJ
≥
0°C (Note 8)
q
q
q
MIN
3.270
3.235
3.270
3.235
3.564
3.500
3.528
TYP
3.300
3.300
3.300
3.300
3.600
MAX
3.330
3.365
3.330
3.365
3.636
3.672
3.672
UNITS
V
V
V
V
V
V
V
2
UU
U
U
U
W
W W
U
W
ORDER PART NUMBER
V
IN
V
OUT
GND
LT1083CP-5
LT1083CP-12
LT1084CP-5
LT1084CP-12
LT1085CM-3.3
LT1085CM-3.6
LT1083/84/85 Fixed
ELECTRICAL CHARACTERISTICS
PARAMETER
Output Voltage
CONDITIONS
LT1085-3.6
5V
≤
V
IN
≤
15V, 0
≤
I
OUT
≤
2.5A (Note 8)
V
IN
= 4.75V, I
OUT
= 3A, T
J
≥
0°C
V
IN
= 4.75V, I
OUT
= 2.5A, T
J
≥
0°C
V
IN
= 4.75V, I
OUT
= 1.5A, T
J
> 0°C
I
OUT
= 0mA, T
J
= 25°C, V
IN
= 8V (K Package Only)
0
≤
I
OUT
≤
I
FULLOAD
, 6.5V
≤
V
IN
≤
20V (Notes 3, 5, 6, 8)
I
OUT
= 0mA, T
J
= 25°C, V
IN
= 15V (K Package Only)
0
≤
I
OUT
≤
I
FULLOAD
, 13.5V
≤
V
IN
≤
25V (Notes 3, 5, 6, 8)
I
OUT
= 0mA, T
J
= 25°C, 4.8V
≤
V
IN
≤
15V
4.8V
≤
V
IN
≤
15V, I
OUT
= 0mA, T
J
= 25°C
q
LT1085-3.6
LT1083/4/5-5
LT1083/4/5-12
Load Regulation
LT1084-3.3
LT1085-3.3
LT1085-3.6
LT1083/4/5-5
LT1083/4/5-12
Dropout Voltage
4.8V
≤
V
IN
≤
15V, I
OUT
= 0mA, T
J
= 25°C
q
I
OUT
= 0mA, T
J
= 25°C, 6.5V
≤
V
IN
≤
20V (Notes 1, 2)
q
I
OUT
= 0mA, T
J
= 25°C, 13.5V
≤
V
IN
≤
25V (Notes 1, 2)
q
V
IN
= 5V, 0
≤
I
OUT
≤
5A, T
J
= 25°C
q
V
IN
= 5V, 0
≤
I
OUT
≤
3A, T
J
= 25°C
q
V
IN
= 5.25V, 0
≤
I
OUT
≤
3A, T
J
= 25°C
q
V
IN
= 8V, 0
≤
I
OUT
≤
I
FULLLOAD,
T
J
= 25°C (Notes 1, 2, 3, 5)
q
V
IN
= 15V, 0
≤
I
OUT
≤
I
FULLLOAD,
T
J
= 25°C (Notes 1, 2, 3, 5)
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
MIN
3.528
3.350
3.450
3.528
4.950
4.900
11.880
11.760
TYP
MAX
3.672
3.672
3.672
3.672
5.050
5.100
12.120
12.240
6
6
6
6
6
6
10
10
25
25
15
20
15
20
15
20
20
35
36
72
1.5
1.5
1.5
1.5
UNITS
V
V
V
V
V
V
V
V
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
V
V
V
V
A
A
A
A
A
A
A
A
mA
mA
mA
mA
mA
%/W
%/W
%/W
dB
LT1083/4/5-5
LT1083/4/5-12
Line Regulation
LT1084-3.3
LT1085-3.3
q
Current Limit
Quiescient Current
Thermal Regulation
Ripple Rejection
LT1084/5-3.3
∆V
OUT
= 33mV, I
OUT
= I
FULL LOAD
(Notes 4, 5)
LT1085-3.6
∆V
OUT
= 36mV, I
OUT
= I
FULL LOAD
(Notes 4, 5)
LT1083/4/5-5
∆V
OUT
= 50mV, I
OUT
= I
FULL LOAD
(Notes 4, 5)
LT1083/4/5-12
∆V
OUT
= 120mV, I
OUT
= I
FULL LOAD
(Notes 4, 5)
LT1083-5
V
IN
= 10V
LT1083-12
V
IN
= 17V
LT1084-3.3
V
IN
= 8V
LT1084-5
V
IN
= 10V
LT1084-12
V
IN
= 17V
LT1085-3.3/3.6 V
IN
= 8V
LT1085-5
V
IN
= 10V
LT1085-12
V
IN
= 17V
LT1084-3.3
V
IN
= 18V
LT1085-3.3
V
IN
= 18V
LT1085-3.6
V
IN
= 18V
LT1083/4/5-5
V
IN
≤
20V
LT1083/4/5-12
V
IN
≤
25V
LT1083-5/12
T
A
= 25°C, 30ms pulse
LT1084-3.3/5/12
LT1085-3.3/3.6/5/12
f = 120Hz, C
OUT
= 25µF Tantalum, I
OUT
= I
FULLLOAD
LT1084-3.3
f = 120Hz, C
OUT
= 25µF Tantalum, I
OUT
= 5A, V
IN
= 6.3V
8.0
8.0
5.5
5.5
5.5
3.2
3.2
3.2
5.000
5.000
12.000
12.000
0.5
1.0
0.5
1.0
0.5
1.0
0.5
1.0
1.0
2.0
3
7
3
7
3
7
5
10
12
24
1.3
1.3
1.3
1.3
9.5
9.5
6.5
6.5
6.5
4.0
4.0
4.0
5.0
10.0
5.0
10.0
5.0
10.0
5.0
10.0
5.0
10.0
0.002 0.010
0.003 0.015
0.004 0.020
72
q
60
3
LT1083/84/85 Fixed
ELECTRICAL CHARACTERISTICS
PARAMETER
Ripple Rejection
CONDITIONS
LT1085-3.3
LT1085-3.6
LT1083/4/5-5
LT1083/4/5-12
f = 120Hz, C
OUT
= 25µF Tantalum, V
IN
= 6.3V, I
OUT
= 3A
f = 120Hz, C
OUT
= 25µF Tantalum, V
IN
= 6.6V, I
OUT
= 3A
V
IN
= 8V (Note 5)
V
IN
= 15V (Note 5)
q
q
q
q
q
MIN
60
60
60
54
TYP
72
72
68
60
0.5
0.03
0.003
0.6/1.6
0.5/1.6
0.75/2.3
0.65/2.3
0.65/2.7
0.9/3.0
0.7/3.0
0.7/3.0
MAX
UNITS
dB
dB
dB
dB
%
%
%
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
Temperature Stability
Long Term Stability
RMS Output Noise
(% of V
OUT
)
Thermal Resistance
Junctrion-to-Case
T
A
= 125°C, 1000 Hrs.
T
A
= 25°C,
10Hz =
≤
f
≤
10kHz
Control Circuitry/Power Transistor (See Applications Information)
LT1083
K Package
P Package
LT1084
K Package
P Package
T Package
LT1085
K Package
T Package
DD Package
1.0
The
q
denotes the specifications which apply over the full operating
temperature range.
Note 1:
See thermal regulation specifications for changes in output voltage
due to heating effects. Load and line regulation are measured at a constant
junction temperature by low duty cycle pulse testing.
Note 2:
Line and load regulation are guaranteed up to the maximum power
dissipation (60W for the LT1083, 45W for the LT1084 (K, P), 30W for the
LT1084 (T) and 30W for the LT1085). Power dissipation is determined by
the input/output differential and the output current. Guaranteed maximum
power dissipation will not be available over the full input/output range.
Note 3:
I
FULL LOAD
is defined in the current limit curves. The I
FULLLOAD
curve is defined as the minimum value of current limit as a function of
input to output voltage. Note that the 60W power dissipation for the
LT1083 (45W for the LT1084 (K, P), 30W for the LT1084 (T), 30W for the
LT1085) is only achievable over a limited range of input to output voltage.
Note 4:
Dropout voltage is specified over the full output current range of
the device. Test points and limits are shown on the Dropout Voltage curve.
Note 5:
For LT1083 I
FULL LOAD
is 5A for – 55°C
≤
T
J
≤
– 40°C and 7.5A for
T
J
≥
– 40°C.
Note 6:
1.7V
≤
(V
IN
– V
OUT
)
≤
25V for LT1084 at – 55°C
≤
T
J
≤
– 40°C.
Note 7:
Dropout voltage 1.7V maximum for LT1084 at – 55
≤
T
J
≤
– 40°C.
Note 8:
Full load current is not available at all input-output voltages.
See Notes 2,3,5.
TYPICAL PERFORMANCE CHARACTERISTICS
LT1083 Dropout Voltage
MINIMUM INPUT/OUTPUT DIFFERENTIAL (V)
2
INDICATES GUARANTEED TEST POINT
SHORT-CIRCUIT CURRENT (A)
–40°C
≤
T
J
≤
150°C
0°C
≤
T
J
≤
125°C
12
10
8
6
4
2
0
0
20
30
15
25
5
10
INPUT/OUTPUT DIFFERENTIAL (V)
35
–55°C
I
FULL LOAD
GUARANTEED
25°C
150°C
OUTPUT VOLTAGE DEVIATION (%)
1
T
J
= 150°C
T
J
= 25°C
T
J
= –55°C
0
0
1
2
3 4 5 6 7 8
OUTPUT CURRENT (A)
LT1083/4/5 FIXED G01
4
U W
9
LT1083 Short-Circuit Current
0.10
LT1083 Load Regulation
∆I
= 7.5A
0.05
0
–0.05
–0.10
–0.15
–0.20
–50 –25
10
0
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083/4/5 FIXED G03
LT1083/4/5 FIXED G02
LT1083/84/85 Fixed
TYPICAL PERFORMANCE CHARACTERISTICS
LT1084 Dropout Voltage
MINIMUN INPUT/OUTPUT DIFFERENTIAL (V)
2
INDICATES GUARANTEED TEST POINT
SHORT-CIRCUIT CURRENT (A)
–55°C
≤
T
J
≤
150°C
0°C
≤
T
J
≤
125°C
OUTPUT VOLTAGE DEVIATION (%)
1
T
J
= –55°C
T
J
= 150°C
T
J
= 25°C
0
0
1
3
4
2
OUTPUT CURRENT (A)
5
6
LT1083/4/5 FIXEDG04
LT1085 Dropout Voltage
MINIMUM INPUT/OUTPUT DIFFERENTIAL (V)
2
INDICATES GUARANTEED TEST POINT
–55°C
≤
T
J
≤
150°C
0°C
≤
T
J
≤
125°C
SHORT-CIRCUIT CURRENT (A)
5
4
3
–55°C
2
1
0
I
FULL LOAD
GUARANTEED
25°C
150°C
OUTPUT VOLTAGE DEVIATION (%)
1
T
J
= 25°C
T
J
= 150°C
T
J
= –55°C
0
0
2
3
1
OUTPUT CURRENT (A)
4
LT1083/4/5 FIXED G07
LT1083/4/5-5 Ripple Rejection
80
70
V
RIPPLE
≤
3V
P-P
V
RIPPLE
≤
0.5V
P-P
RIPPLE REJECTION (dB)
RIPPLE REJECTION (dB)
60
50
40
30
20
I
OUT
= I
FULL LOAD
10
0
10
100
(V
IN
– V
OUT
)
≥
3V
(V
IN
– V
OUT
)
≥
V
DROPOUT
80
70
60
50
40
30
20
10
f
R
= 20kHz
V
RIPPLE
≤
0.5V
P-P
f
R
= 120Hz
V
RIPPLE
≤
3V
P-P
OUTPUT VOLTAGE CHANGE (%)
1k
10k
FREQUENCY (Hz)
U W
1083/4/5 FIXED G10
LT1084 Short Circuit Current
10
9
8
7
6
5
4
3
2
1
0
0
20
15
10
25
30
5
INPUT/OUTPUT DIFFERENTIAL (V)
35
I
FULL LOAD
GUARANTEED
–55°C
150°C
25°C
0.05
0
–0.05
–0.10
–0.15
0.10
LT1084 Load Regulation
∆I
= 5A
–0.20
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083/4/5 FIXED G06
LT1083/4/5 FIXED G05
LT1085 Short-Circuit Current
6
0.10
LT1085 Load Regulation
∆I
= 3A
0.05
0
–0.05
–0.10
–0.15
–0.20
–50 –25
0
20
30
15
25
5
10
INPUT/OUTPUT DIFFERENTIAL (V)
35
0
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083/4/5 FIXED G09
LT1083/4/5 FIXED G08
LT1083/4/5-5 Ripple Rejection
vs Current
100
90
1.0
2.0
Temperature Stability
0
–1.0
100k
0
0
0.8
0.2
0.6
0.4
OUTPUT CURRENT (0 TO I
FULL LOAD
)
1.0
–2.0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
LT1183/4/5 FIXED G12
1083/4/5 FIXED G11
5
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